I think it's harsh to lay blame at the door of Zlatan's supporting cast. Other than Pogba he is the only attack minded player to have been given a consistent run in the team. The most number of consecutive games a wide player (or #10) has had in the team has been 4. Compare that to 13 and 11 for Pogba and Zlatan respectively. It's been hard for any of those guys to get a consistent run going. Sure it's been a figuring out process, but I think it has dented some guys confidence and they are snatching at chances, almost trying too hard to impress. I think what we need now is some continuity and allow Martial and Mkhitaryan to make those wide roles their own for the remainder of the season.
Also something which has been touched on slightly by some earlier... where are our free goals? We don't seem to be getting anything cheap just now. Goals from corners, penalties, OGs. The amount of corners we have you would think at some point some defender is going to shank a clearance or something! Gary Cahill (Chelsea defender) has more goals than our entire defence and centre midfield excluding Pogba:
Cahill: 6
Bailly, Jones, Rojo, Smalling, Blind, Valencia, Shaw, Darmian, Young, Carrick, Herrera, Fellaini: 5
Everything we get we are having to fight tooth and nail for. Feels like we need to craft 4 or 5 good chances for one goal. The Reading game was a great example, Rashford had 4 good chances and scored one. He then got given a 'free goal' (yeah he worked hard pressing the keeper, but free in the sense that we didn't need to break down the defence for it). All of a sudden instead of having 1 goal in 4 chances (25%), he has 2 from 4 (50%).